6-lobe (TX) go/no-go socket gages

Universal’s Gages are heat treated, thermally stabilized, and surface treated. This provides additional hardness for maximum wear. Gage probes are calibrated to dimensions and tolerances as specified and are traceable to the National Institute of Standards and Technology.

6-lobe (TX) go/no-go socket gages / TMF/TXQ-806.1 - #2175

For external drives.
Standard references TMF / TXQ - 806.1

More informations here.